There have been used a variety of coloring pigments in areas such as coatings, plstics, printing inks and cosmetics. In recent years, there have been used light-interference pearl pigments which are obtained by coating the surface of flaky powder with titanium oxide, iron oxide or the like to obtain a bright color and a certain kind of design on products.
In commonly used pearl pigments, which are obtained by coating the surface of flaky powder with a colorless metal oxide such as titanium oxide, the thickness of the coating is varied to produce a variety of interference colors. It is known that, for brighter interference colors, materials with different refractive indexes should be multi-layered. There have been proposed various methods for multi-layering such materials, and there are pearl pigments of multi-layer construction on the market, indeed. Meanwhile, in pearl pigments of multi-layer construction obtained using a color metallic compound such as iron oxide, it is also possible to obtain bright interference colors. Such pigments are, however, affected by the color of the color metallic compound, and there have been only pearl pigments having a color of similar shade to that of the color compound. For example, pearl pigments obtained using iron oxide each have a color of a reddish shade. In other words, no multi-layered pearl pigment in which the color of the color compound used as an inner layer is controlled and thus interference colors are produced without restrictions by the color of the color metallic compound itself has been known.
For example, in JP-A-6-100794 there are proposed multi-layer pearl pigments obtained by forming an iron oxide layer on a platelet-shaped powder and coating the powder with the iron oxide layer with an aluminum compound. This proposal relates to pigments having a color of a reddish shade and a process for producing the same, and therefore provides only pearl pigments having a color of a reddish shade. In JP-A-7-11161 and JP-A-8-259840, there are proposed multi-layer pearl pigments obtained by coating iron oxide coated platelet-shaped powder with a colorless metal oxide such as titanium oxide. These proposals are, however, different from the above described proposal only in the kind of the colorless metal oxide used, and like the above proposal, they provide only pearl pigments having a color of a reddish shade. There is nothing described of obtaining pigments having a hue other than red in those specifications.
Meanwhile, of cosmetics using coloring pigments, make-up cosmetics are required to change users' skin texture when they apply them to their skin, and powders that give rise to strong diffuse reflection or specular reflection are used to control users' skin tone and texture. For example, titanium oxide as a powder that gives rise to strong diffuse reflection or a spherical powder is blended with make-up cosmetics to create a matte finish, or a platelet-shaped powder, such as mica, sericite or talc, which gives rise to strong specular reflection is blended with make-up cosmetics to impart a lustrous finish. To cover color non-uniformity such as pigmented spots or freckles, pigments having good hiding power such as titanium dioxide or iron oxide are also blended with make-up cosmetics.
However, the use of pigments with good hiding power causes a problem of producing an unnatural look, whereas the use of powders with poor hiding power to adjust the skin tone and texture causes a problem of a decrease in the covering effect on the color non-uniformity, etc., of the skin.
To overcome the above described problems, considerations have been given to using pearl pigments that have good hiding power and are capable of controlling skin luster to change the hue of the skin, in recent years. For example, when a titanium-oxide coated pearl pigment is used in cosmetics for imparting a lustrous finish to the skin, skin luster can be produced in such a direction that regular reflection of light occurs, due to the specular reflection by the pigment, but not through an angle other than that of specular reflection, and at such an angle the cosmetics impart a whitish look of the powder itself. Accordingly, when a user applies the cosmetics over a wide range, for example, to the entire face, the portion directly facing its observer provides a lustrous look, but the portion not directly facing its observer provides a whitish and powdery look, resulting in a tendency toward an unnatural finish. JP-A-2003-212.722 describes a powder for producing natural skin luster which is obtained by coating the surface of titanium mica with alumina and silica in this order. This powder, however, still leaves unresolved the problem of a whitish and powdery look produced on the portion that does not directly face its observer.
On the other hand, there are pearl pigments in which a coating is applied onto the colored metal oxide layer, such as iron oxide layer, on the market. In JP-A-7-11161 and 8-259840, there are proposed multi-layer pearl pigments obtained by coating an iron-oxide coated platelet-shaped powder with a colorless metal oxide such as titanium oxide. However, the pearl pigments obtained are all reddish ones, and it is impossible to express a bright charming skin tone and texture by using them.